import { createWasmCodec } from "./wasm-base.js";

function mp3Magic(bytes: Uint8Array): boolean {
    if (bytes.byteLength < 2) return false;
    // MPEG audio sync word (11 bits) — 0xFFE mask on first two bytes
    if (bytes[0] === 0xff && (bytes[1]! & 0xe0) === 0xe0) return true;
    // ID3v2 prefix requires three bytes
    if (
        bytes.byteLength >= 3 &&
        bytes[0] === 0x49 &&
        bytes[1] === 0x44 &&
        bytes[2] === 0x33
    )
        return true;
    return false;
}

/** Lazy MP3 codec backed by `@audio/decode-mp3`. */
export const Mp3Codec = createWasmCodec({
    name: "mp3",
    extensions: ["mp3", "mpeg"],
    mimeTypes: ["audio/mpeg", "audio/mp3"],
    module: "@audio/decode-mp3",
    magic: mp3Magic,
    supportsEncode: true,
    load: () =>
        // @ts-expect-error optional dependency resolved at runtime
        import("@audio/decode-mp3"),
});